Wire and methods for preparing a wire to receive a contact element

ABSTRACT

A method is provided for preparing a wire for installation of a terminal. The method comprises removing an insulating layer from a conductor to expose a portion of a conductor. The method further includes attaching a conductive foil layer to a portion of the exposed portion of the conductor by applying pressure to the conductive foil layer.

TECHNICAL FIELD

The articles and methods described below generally relate to the fieldof preparing a wire to receive a contact element.

BACKGROUND

Automotive cables, such as a battery cable, can include an aluminumconductor which can be lighter and less expensive than conventionalcopper conductors. A contact element, such as a ring terminal, iscrimped or otherwise secured to a bare end of the aluminum conductor toform a terminated end. The contact element is typically made from copperbased alloys such as brass, for example, or another material that isdifferent than aluminum.

The bare end of aluminum conductor, however, can be susceptible tooxidation (e.g., sapphire oxidation) which can inhibit conductivitybetween the bare end and the contact element and thus can prevent propertermination with a contact element. The aluminum conductor can also besusceptible to galvanic corrosion when it is terminated to a materialthat is more basic than aluminum, such as brass, and when moisture ispresent at the interface between the conductor and the contact element.The galvanic corrosion can cause aluminum dissolution which canadversely affect the conductivity between the aluminum conductor and thecontact element. Once terminated, the aluminum conductor can be moresusceptible to mechanical creep at its terminated end at lowtemperatures (e.g., 80 degrees C.) than conventional copper conductorswhich can result in undesirable impedances. The aluminum conductor isalso weaker than a copper conductor which can result in the aluminumconductor being easier to pull out of the contact element aftertermination.

SUMMARY

In accordance with one embodiment, a method for preparing a wire toaccept a contact element is provided. The wire comprises a conductor andan insulating layer surrounding the conductor. The conductor is formedof a first material. The method comprises removing the insulating layerfrom the conductor to expose a portion of the conductor. The methodfurther comprises joining a conductive foil layer and at least a portionof the exposed portion of the conductor together. The conductive foillayer is formed of a second material.

In accordance with another embodiment, a method for installing a contactelement on a wire is provided. The wire comprises a conductor. Theconductor comprises an exposed portion and is formed of a firstmaterial. The method comprises joining a conductive foil layer and theexposed portion of the conductor together. The method further comprisessecuring the contact element to the exposed portion of the conductor andthe conductive foil layer. The conductive foil layer is formed of asecond material. The terminal is formed of a third material.

In accordance with yet another embodiment, a terminated wire comprises aconductor. The conductor comprises an exposed portion and is formed of afirst material. The terminated wire is prepared by the process ofjoining a conductive foil layer and an exposed portion of the conductortogether and securing a contact element to the exposed portion of theconductor and the conductive foil layer. The conductive foil layer isformed of a second material. The contact element is formed of a thirdmaterial.

In accordance with yet another embodiment, a terminated wire comprises awire, a conductive foil layer, and a contact element. The wire comprisesa conductor. The conductor comprises an exposed portion and is formed ofa first material. The conductive foil layer is formed of a secondmaterial. The contact element is formed of a third material. Theconductive foil layer is joined to the exposed portion of the conductor.The terminal is secured to the exposed portion of the conductor and theconductive foil layer.

BRIEF DESCRIPTION OF THE DRAWINGS

It is believed that certain embodiments will be better understood fromthe following description taken in conjunction with the accompanyingdrawings in which:

FIG. 1 is a perspective view depicting a wire, a conductive foil layer,and a terminal prior to the conductive foil layer being installed on aconductor of the wire, in accordance with one embodiment;

FIG. 2 is a perspective view depicting the conductive foil layerinstalled on the wire of FIG. 1;

FIG. 3 is a perspective view of the terminal installed on the wire ofFIG. 1;

FIG. 4 is a cross-sectional view taken along the line 4-4 in FIG. 3;

FIG. 5 is a perspective view depicting a wire, a conductive foil layer,and a terminal prior to the conductive foil layer being installed on aconductor of the wire, in accordance with another embodiment;

FIG. 6 is a perspective view of the terminal installed on the wire ofFIG. 5;

FIG. 7 is a cross-sectional view taken along the line 7-7 in FIG. 6;

FIG. 8 a perspective view depicting a wire, a conductive foil layer, anda terminal prior to the conductive foil layer being installed on aconductor of the wire, in accordance with another embodiment;

FIG. 9 is a perspective view depicting a wire and ferrule prior to theferrule being installed on a conductor of the wire, in accordance withanother embodiment; and

FIG. 10 is a perspective view of the wire of FIG. 9, but with theferrule installed on the conductor.

DETAILED DESCRIPTION

In connection with the views and examples of FIGS. 1-10, wherein likenumbers indicate the same or corresponding elements throughout theviews, FIG. 1 illustrates a wire 10 having a conductor 12 and aninsulating layer 14 surrounding the conductor 12. A portion of theinsulating layer 14 is shown to be removed from the conductor 12 toexpose a bare portion 16 of the conductor 12. The insulating layer 14can be removed with any of a variety of suitable methods, such asthrough interaction with a set of wire strippers. Although amulti-strand insulated conductor is shown, it will be appreciated thatany of a variety of suitable alternative conductors can be used havingdifferent quantities/sizes of strands, including a conductor having anindividual strand (e.g., a solid conductor) and/or being devoid ofinsulation (e.g., a grounding conductor.

As illustrated in FIGS. 1 and 2, a conductive foil layer 18 can beattached to a portion of the bare portion 16 of the conductor 12. In oneembodiment, the conductive foil layer 18 can be wrapped around the bareportion 16 of the conductor 12, as illustrated in FIG. 2, and pressurecan be applied to the conductive foil layer 18 (in the direction of thearrows P). In one embodiment, the application of pressure to theconductive foil layer 18 can be the result of simply overlying theconductive foil layer 18 onto the bare portion 16 of the conductor 12(e.g., by grasping the ends of the conductive foil layer 18 and wrappingit around the bare portion 16). In certain embodiments, the desiredpressure can be applied by hand, with a tool (e.g., pliers), or any of avariety of other suitable methods.

Once the conductive foil layer 18 has been provided onto the bareportion 16 of the conductor 12, the bare portion 16 of the conductor 12and the conductive foil layer 18 can be joined together. In oneembodiment, the bare portion 16 and the conductive foil layer 18 can bejoined together through welding, such as through ultrasonic welding, forexample. Welding the bare portion 16 and the conductive foil layer 18together can bond the conductive foil layer 18 to the conductor 12 aswell as bond the strands of the conductor 12 together to form anamalgamated mass (e.g., a nugget). Welding can also help break apart anyoxidation formed on the conductor 12 that might adversely affect theconductivity between the conductor 12 and the conductive foil layer 18.Welding can accordingly enhance the conductivity characteristics betweenthe conductor 12 and the conductive foil layer 18.

Once the conductor 12 and the conductive foil layer 18 have been joinedtogether, a terminal 20 can be slid over the conductive foil layer 18and secured to the amalgamated mass of the bare portion 16 and theconductor 12, such as with a crimping tool, for example, to create aterminated wire 21, as illustrated in FIGS. 3 and 4. In one embodiment,as illustrated in FIG. 3, an exterior surface 22 of a crimping portion24 of the terminal 20 can be reinforced, such as by applying solder 26at a separation point 28 of the crimping portion 24, to enhance thedurability of the connection between the terminal 20 and the conductor12. In certain embodiments, the terminal 20 can be nickel plated, orplated with another conductive material, prior to attachment of theterminal 20 to the conductor 12. In such an embodiment, the nickelplating can protect the terminal from galvanic corrosion to enhance theconductivity between the conductor 12 and the material that forms theterminal 20 (e.g., brass). The terminated end can additionally oralternatively be dipped in molten solder to enhance durability of theterminated wire 21. It is to be appreciated that although the terminal20 is shown to be a ring terminal, it is to be appreciated that any of avariety of suitable alternative contact elements, such as a slottedterminal, a bus bar, or a termination block, for example, can beattached to the wire 10. It is also to be appreciated that theterminated wire 21 is contemplated for use in a variety of suitableapplications, such as, for example, as a vehicular battery cable.

The conductor 12 and the conductive foil layer 18 can be formed ofdifferent conductive materials with the conductive foil layer 18 havingabout the same or higher conductivity than the conductor 12. As aresult, when the conductive foil layer 18 is interposed between theconductor 12 and the terminal 20, the conductive foil layer 18 canenhance the overall conductivity between the conductor 12 and theterminal 20 as compared to the conductive foil layer 18 not beingpresent (i.e., the conductor 12 and the terminal 20 being entirely incontact with each other). In one embodiment, the conductor 12 can beformed of aluminum or an aluminum alloy, the conductive foil layer 18can be formed of copper, and the terminal 20 can be formed of brass. Insuch an embodiment, the copper of the conductive foil layer 18 can allowthe interaction between the aluminum conductor 12 and the brass terminal20 to be more conductive than crimping the brass terminal 20 directly tothe aluminum conductor 12 (which in some instances can benon-conductive). It is to be appreciated that the conductive foil layer18 can be formed of a material that is as conductive as or moreconductive than the conductor 12. In certain embodiments, the conductor12 can be formed of a conductive material having a conductivity of about3.5*10⁷ S/m (at 20 degrees C.) or less, and the conductive foil layer 18can be formed of conductive material having a conductivity of about4.1*10⁷ S/m (at 20 degrees C.) or more. In other embodiments, theconductor 12 can be formed of a conductive material that issubstantially susceptible to oxidation, such as an aluminum alloy, achromium alloy, and/or a magnesium alloy, and the conductive foil layer18 can be formed of conductive material that is not substantiallysusceptible to oxidization such as a copper alloy, silver, nickel,and/or gold. It is to be appreciated that the different metals describedabove for the conductor 12, the conductive foil layer 18, and theterminal 20 can be any of a variety of different metals or metal alloys,such as, for example copper or copper alloys, such as brass.

As illustrated in FIG. 1, the conductive foil layer 18 is shown to havea length L1, a width W, and a thickness T and the bare portion 16 of theconductor 12 is shown to have a length L2, a diameter D, and acircumference C. In one embodiment, the length L1 and width W of theconductive foil layer 18 can be less than the circumference C and thelength L2 of the bare portion 16 of the conductor 12, respectively, suchthat when the conductive foil layer 18 is attached to the conductor 12,the conductive foil layer 18 neither reaches the end of the conductor 12nor completely surrounds it. In another embodiment, the length L1 of theconductive foil layer 18 can be more than the circumference C of thebare portion 16 of the conductor 12, respectively, such that when theconductive foil layer 18 is attached to the conductor 12, the conductivefoil layer 18 overlaps at its ends such that it entirely surrounds thebare portion 16. In certain embodiments, the diameter D of the conductorcan be significantly more than the thickness T of the conductive foillayer 18, and can in certain embodiments have a ratio of between about100:1 and about 500:1 and in certain embodiments can have a ratio ofabout 200:1. In one embodiment, for a 0 AWG wire, the length L1 can beabout 40 mm, the width W can be about 18 mm, the thickness T can beabout 0.035 mm, the length L2 can be about 20 mm, the diameter D can beabout 8 mm, and the circumference C can be about 25 mm. It will beappreciated that a layer described herein as being a foil, such asconductive foil layer 18, should be understood to mean that the layer isa sheet-like substrate having a length and width that are substantiallygreater than the thickness of the substrate. In certain embodiments,ratio of the combined length and width of the layer to the thickness ofthe layer can be between about 500:1 to about 100,000:1. In certainembodiments, the ratio can be about 10,000:1 to about 25,000:1 andpreferably about 14,000:1

In some embodiments, the bare portion 16 of the conductor 12, alone orin combination with the conductive foil layer 18, can be cleaned beforeor after application of the conductive foil layer 18 to remove anyoxides on the conductor 12 and/or between the conductor 12 and theconductive foil layer thus enhancing the effectiveness of theconductivity between the conductor 12, the conductive foil layer 18, andthe terminal 20. In one embodiment, the conductor 12 and/or conductivefoil layer 18 can be cleaned via a plasma treatment performed by ablown-ion air system (not shown). The blown-ion air system can forcepressurized air towards an electrode, through a narrow nozzle, and ontothe bare portion 16. The electrode creates positively charged ions inthe pressurized air which is then accelerated by the nozzle and providedonto the bare portion 16 of the conductor 12. The positively chargedions in the airstream positively charge the outer surface of the bareportion 16 thereby increasing its surface energy to remove any oxides.In another embodiment, the conductor 12 and/or conductive foil layer 18can be cleaned via a high temperature induction heating process thatapplies a flame to the conductor 12 and/or conductive foil layer 18using any of a variety of fuels, such as, for example, hydrogen gas,alcohol, and/or acetylene.

In certain embodiments, the bare portion 16 of the conductor 12 and theconductive foil layer 18 can be joined by soldering such as by dippingthe bare portion 16 and the conductive foil layer 18 together in amolten material (e.g., such as molten tin) or resistance soldering thebare portion 16 and the conductive foil layer 18 together, for example,both of which can enhance the conductivity between the bare portion 16,the conductive foil layer 18, and the terminal 20. It is to beappreciated that cleaning the bare portion 16 and/or the conductive foillayer 18 can encourage the application of solder. However, the solderingcan be performed in addition to the welding or in addition to or in lieuof the cleaning described above. It is also to be appreciated that thebare portion 16 and/or the conductive foil layer 18 can undergo any of avariety of other suitable treatment processes to prepare for affixationof the terminal 20.

FIGS. 5-7 illustrate a wire 110, a conductive foil layer 118 and aterminal 120 that are similar to, or the same in many respects as, thewire 10, the conductive foil layer 18 and the terminal 120,respectively, illustrated in FIGS. 1-4. For example, the wire 110 caninclude a conductor 112, an insulating layer 114, a bare portion 116,and a conductive foil layer 118. However, the conductive foil layer 118can be joined to the bare portion 116 of the conductor 112 by applyingpressure to the conductive foil layer 118 (in the direction of thearrows P) and without any welding (ultrasonic or otherwise). In such anarrangement, the terminal 20 can be slid over the bundle of strands(e.g., 123) at the bare portion 16 and secured to the bundle of strands(e.g., 123), such as with a crimping tool, for example. An exteriorsurface 122 of a crimping portion 124 of the terminal 120 can bereinforced, such as by applying solder 126 at a separation point 128 ofthe crimping portion 124.

FIG. 8 illustrates a wire 210, a conductive foil layer 218 and aterminal 220 that are similar to, or the same, in many respects as thewire 10, the conductive foil layer 18 and the terminal 20, respectively,illustrated in FIGS. 1-4. For example, the wire 210 can include aconductor 212, an insulating layer 214, and a bare portion 216. Theconductive foil layer 218, however, can be a corrugated screen having aplurality of elevated portions (e.g., points) distributed along upperand lower surfaces (upper surface 230 shown). When the conductive foillayer 218 is attached to the bare portion 216 of the conductor 212, thepoints can abrade the bare portion 216 of the conductor 212 (e.g.,remove any oxidation) to facilitate effective electrical contact betweenthe bare portion and the conductive foil layer 218. If the bare portion216 and the conductive foil layer 218 are joined by soldering, asdescribed above, the solder can collect in pockets defined between thepoints to facilitate effective bonding between the bare portion 216 andthe conductive foil layer 218. In one embodiment, the conductive foillayer 218 can be formed of nickel and the conductor 212 can be formed ofaluminum 212.

FIGS. 9-10 illustrate a wire 310 that is similar to, or the same, inmany respects as the wire 10 illustrated in FIGS. 1-4. For example, thewire 310 can include a conductor 312, an insulating layer 314, and abare portion 316. A ferrule 331, however, can be provided in lieu of, orin addition to, a conductive foil layer (e.g., 18). The ferrule 331 canbe joined to the bare portion similarly as described above and aterminal (not shown) can then be secured thereto.

Another alternative embodiment of a terminated wire (e.g., analternative terminated wire) is also contemplated. The alternativeterminated wire can be similar in many respects to the terminated wire21 described above except that the alternative terminated wire does notinclude a conductive foil layer (e.g., 18). To prepare the alternativeterminated wire, a portion of an insulating layer (e.g., 14) can beremoved from a conductor (e.g., 12) to expose a bare portion (e.g., 16)of the conductor (e.g., 12). The bare portion can then be cleaned (e.g.,with a plasma treatment) and welded (e.g., through ultrasonic welding)to bind individual strands of the conductor together. The steps ofcleaning and welding can be performed in any order. Once welded, thebare portion can be soldered (e.g., through tin dipping or resistivesoldering). A terminal (e.g., 20) can then be attached to the bareportion insulating layer to create the alternative terminated wire. Inone embodiment, the conductor 112 can be formed of aluminum and theconductive foil layer can be formed of nickel.

EXAMPLES

Testing was conducted on a terminated wire similar to the terminatedwire 21 described above. The terminated wire that was tested was a 0 AWG( 1/0) aluminum wire having a bare portion (e.g., 14) measuring about 20mm, a copper conductive foil layer (e.g., 18) having a length (e.g., L1)of about 40 mm, a width (e.g., W) of about 18 mm, and a thickness (e.g.,T) of about 0.035 mm, and a brass terminal. The copper conductive foillayer was manually wrapped onto the bare portion and then wasultrasonically welded to form a nugget. A terminal was then crimped ontothe nugget. Ten separate resistance tests were then performed to measurethe resistance between the conductor and the terminal (e.g., betweenpoints A and B illustrated on FIG. 3). Each test resulted in aresistance between 0.041 Ohms and 0.045 Ohms, having an exampleresistance of 0.043 Ohms. The maximum allowable resistance for use as avehicular battery cable is 0.057 Ohms.

Comparative testing was also conducted to compare the results fordifferent terminations of a 0 AWG ( 1/0) aluminum wire having a bareportion (e.g., 14) measuring about 20 mm, a copper conductive foil layer(e.g., 18) having a length (e.g., L1) of about 40 mm, a width (e.g., W)of about 20 mm, and a thickness (e.g., T) of about 0.035 mm, and a brassterminal. A variety of different terminated wires were assembled usingcertain of the methodologies described above and resistance tests wereperformed on the terminated wires. The results of the resistance testsare as follows:

Example Termination Method Resistance (Ohms) Example #1 Bare Conductorwith Terminal Open Circuit Crimped Directly to Bare (high resistance)Conductor Example #2 Terminated Conductor Prepared 0.345 milliohms andTerminated Without Conductive Foil Layer as Follows: 1. UltrasonicallyWeld Bare Conductor 2. Plasma Clean Welded Bare Conductor 3. Dip BareConductor in Molten Solder 4. Crimp Terminal to Soldered End of BareConductor. 5. Resistance Solder Outer Surface of Terminal Example #3Terminated Conductor Prepared 0.179 milliohms and Terminated WithoutConductive Foil Layer as Follows: 1. Plasma Clean Bare Conductor 2.Ultrasonically Weld Bare Conductor 3. Plasma Clean Bare Conductor 4. DipBare Conductor in Molten Solder 5. Crimp Terminal to Soldered End ofBare Conductor. 6. Resistance Solder Outer Surface of Terminal Example#4 Terminated Conductor Prepared 0.046 milliohms and Terminated WithSolid Copper Conductive Foil Layer as Follows: 1. Ultrasonically WeldBare Conductor and Conductive Foil Layer Together 2. Dip Welded End inMolten Solder 3. Crimp Terminal to Soldered End of Bare Conductor. 4.Resistance Solder Outer Surface of Terminal

The foregoing description of embodiments and examples of the disclosurehas been presented for purposes of illustration and description. It isnot intended to be exhaustive or to limit the disclosure to the formsdescribed. Numerous modifications are possible in light of the aboveteachings. Some of those modifications have been discussed and otherswill be understood by those skilled in the art. The embodiments werechosen and described in order to best illustrate the principles of thedisclosure and various embodiments as are suited to the particular usecontemplated. The scope of the disclosure is, of course, not limited tothe examples or embodiments set forth herein, but can be employed in anynumber of applications and equivalent devices by those of ordinary skillin the art. Rather it is hereby intended the scope of the invention bedefined by the claims appended hereto. Also, for any methods claimedand/or described, regardless of whether the method is described inconjunction with a flow diagram, it should be understood that unlessotherwise specified or required by context, any explicit or implicitordering of steps performed in the execution of a method does not implythat those steps must be performed in the order presented and may beperformed in a different order or in parallel.

1. A method for preparing a wire to accept a contact element, the wirecomprising a conductor and an insulating layer surrounding theconductor, the conductor being formed of a first material, the methodcomprising: removing the insulating layer from the conductor to expose aportion of the conductor; and joining a conductive foil layer and atleast a portion of the exposed portion of the conductor together,wherein: the conductive foil layer is formed of a second material. 2.(canceled)
 3. The method of claim 2 wherein joining the conductive foillayer and the exposed portion of the conductor together comprisesultrasonically welding the conductive foil layer to the exposed portionof the conductor.
 4. (canceled)
 5. The method of claim 1 whereincleaning the exposed portion of the conductor and the conductive foillayer comprises plasma treating the exposed portion of the conductor andthe conductive foil layer.
 6. (canceled)
 7. The method of claim 1further comprising applying solder to the exposed portion of theconductor and the conductive foil layer by dipping the exposed portionof the conductor and the conductive foil layer into a molten material.8. The method of claim 1 wherein the first material comprises aluminumand the second material comprises copper.
 9. The method of claim 1wherein the conductor has a diameter, the conductive foil layer has athickness, and the ratio of the diameter of the conductor to thethickness of the conductive foil layer is about 200:1.
 10. The method ofclaim 1 wherein the first material is different from the secondmaterial.
 11. A method for installing a contact element on a wire, thewire comprising a conductor, the conductor comprising an exposed portionand being formed of a first material, the method comprising: joining aconductive foil layer and the exposed portion of the conductor together;and securing the contact element to the exposed portion of the conductorand the conductive foil layer, wherein: the conductive foil layer isformed of a second material; and the contact element is formed of athird material. 12-19. (canceled)
 20. The method of claim 11 furthercomprising soldering an exterior surface of the terminal. 21-35.(canceled)
 36. A terminated wire comprising: a wire comprising aconductor, the conductor comprising an exposed portion and being formedof a first material; a conductive foil layer formed of a secondmaterial; a contact element formed of a third material; wherein: theconductive foil layer is joined to the exposed portion of the conductor;the contact element is secured to the exposed portion of the conductorand the conductive foil layer.
 37. The terminated wire of claim 36wherein the wire comprises an insulating layer circumferentiallysurrounding at least a portion of the conductor.
 38. The terminated wireof claim 36 wherein the first material and the second material aredifferent.
 39. The terminated wire of claim 38 wherein the firstmaterial and the third material are different.
 40. The terminated wireof claim 39 wherein the first material comprises an aluminum alloy, thesecond material comprises copper, and the third material comprises acopper alloy.
 41. The terminated wire of claim 40 wherein the thirdmaterial comprises brass. 42-43. (canceled)
 44. The terminated wire ofclaim 36 wherein the conductor has a diameter, the conductive foil layerhas a thickness, and the ratio of the diameter of the conductor to thethickness of the conductive foil layer is about 200:1.
 45. The method ofclaim 1 wherein the conductive foil layer comprises one or more of acorrugated screen, a film, a sheet, and a ferrule.
 46. The terminatedwire of claim 36 wherein the conductive foil layer comprises one or moreof a corrugated screen, a film, a sheet, and a ferrule.
 47. The methodof claim 11 wherein: joining the conductive foil layer and the exposedportion of the conductor together comprises welding the conductive foillayer and the exposed portion of the conductor together; welding theconductive foil layer and the exposed portion of the conductor togethercomprises ultrasonically welding the conductive foil layer and theexposed portion of the conductor together; and cleaning the exposedportion of the conductor and the conductive foil layer comprises plasmatreating the exposed portion of the conductor and the conductive foillayer.
 48. The method of claim 11 further comprising dipping the exposedportion of the conductor and the conductive foil layer into a moltenmaterial.